A multi-functional system for passive heat and water management.

Abstract

We provide an improved multi-functional material system. [Solution] The multifunctional material system has a first side and a second side opposite to the first side. The multifunctional material system comprises a variable permeability layer configured to be applied to a first surface of a substrate, and a desiccant layer applied to the surface of the variable permeability layer, which is adjacent to the substrate and opposite to other surfaces of the variable permeability layer. On both the first and second sides of the multifunctional material system, when humidity is high, water or water vapor flows into the desiccant layer through the variable permeability layer. On both the first and second sides of the multifunctional material system, when humidity is low, water or water vapor flows out of the desiccant layer through the variable permeability layer. The rate of inflow of water or water vapor into the desiccant layer through the variable permeability layer when humidity is high is greater than the rate of outflow of water or water vapor from the desiccant layer through the variable permeability layer when humidity is low.

Description

[Technical Field]

[0001] This application claims the interests of U.S. Provisional Patent Application No. 62 / 725,446, filed on 31 August 2019, entitled "Construction Materials Incorporating A Multifunctional Subsystem For Passive Heat And Water Management In Building Envelopes," which is incorporated herein by reference in its entirety. [Background technology]

[0002] Enclosures such as buildings should ideally possess characteristics such as energy efficiency, comfort, and durability at an affordable cost. However, attempting to achieve these characteristics simultaneously can lead to contradictions. For example, using insulation and increasing the airtightness of a building can improve its energy efficiency. However, this raises concerns about moisture control. In particular, achieving a high R-value (a measure of resistance to thermal conduction) through insulation and airtightness of an enclosure can reduce its permeability to water vapor, potentially increasing the risk of condensation, moisture damage, and mold growth. Therefore, as energy efficiency improves, durability and comfort often decrease. [Overview of the Initiative]

[0003] Various technologies have been developed to improve moisture control. In one embodiment, the membrane of a "smart" vapor retarder exhibits permeability to water vapor that changes with relative humidity. For example, the membrane's permeability increases sharply with rising relative humidity, allowing water to penetrate and dry the wall, while its permeability decreases with falling relative humidity, slowing down the diffusion of water vapor into the wall. However, even with a smart vapor retarder, water vapor moves in the direction of decreasing humidity due to diffusion, so a finite amount of water can enter the wall when the relative humidity rises externally. When relative humidity decreases, the amount of time required to remove water vapor from the wall is approximately the same as the amount of time water vapor was added to the wall. In other words, when the magnitude of the relative humidity gradient across the entire wall is reversed, the smart vapor retarder exhibits time symmetry with respect to water vapor infiltration and emission. Therefore, it can be understood that the smart vapor retarder lacks a mechanism to preferentially suppress water vapor infiltration compared to water vapor emission when relative humidity conditions are reversed.

[0004] Desiccant-based systems are another moisture control technology in current technology. Desiccant systems remove water directly from the air by adsorbing water onto the surface of a desiccant material. When the desiccant material is heated, the adsorbed water is swept away from the surface of the material. This process restores the desiccant's ability to dehumidify the air. In contrast, existing HVAC systems remove water from the air by first cooling the air below the dew point and then reheating the air to the desired temperature. Because HVAC systems require power for both cooling and heating the air in operation, they are significantly less energy-efficient than existing HVAC systems in terms of moisture control. However, while desiccant-based dehumidification systems are more energy-efficient compared to existing HVAC systems, they still consume energy to generate the heat necessary for desiccant regeneration.

[0005] It is understood that improving the energy efficiency of a building often significantly increases construction costs. Generally, adding additional layers for air, humidity, and temperature control significantly increases labor costs. Therefore, multi-functional building materials that can simultaneously regulate water vapor infiltration and exhaust, heat storage and dissipation, and humidification and dehumidification can improve the thermal insulation and humidity control performance of buildings, while also improving energy efficiency and reducing construction labor costs. Furthermore, multi-functional materials that can both humidify and dehumidify without operating mechanical parts or using electricity can further improve efficiency.

[0006] Embodiments of this disclosure provide a multifunctional material system that addresses these challenges. The first function of the multifunctional material system is the storage and release of thermal energy, similar to the function of a phase-change material (PCM). Generally, PCMs can regulate temperature by absorbing latent heat when the ambient temperature rises above the phase transition temperature, or by releasing latent heat when the ambient temperature falls below the phase transition temperature. Existing PCMs can undergo phase changes between liquid and solid states, as in the case of paraffins, and between hydrated and anhydrous states, as in the case of salt hydrates. Multifunctional material systems can adsorb or release heat as water moves between gaseous and condensed states on the surface of the material (e.g., boiling / condensation lines in a aqueous phase diagram). This PCM-like behavior can improve energy efficiency by reducing the energy demand of the HVAC system by an amount equal to the latent heat transferred.

[0007] The second function of a multifunctional material system is the storage and release of water vapor, such as a humidity buffer. Humidity buffering, also known as moisture buffering, characterizes the material's ability to moderate changes in relative humidity by absorbing and releasing water vapor from the surrounding air. Humidity is a key determinant of human comfort, and most people prefer an environment with relative humidity between approximately 35% and 60%. Extremely high humidity creates conditions in which mold, mildew, and dust mites can grow. Extremely low humidity levels can cause dry eyes and skin, increase the risk of respiratory problems, or increase the risk of catching a cold or the flu.

[0008] The third function of the multifunctional material system is to bias the diffusion flow of water vapor in the direction of the desiccant layer, similar to a water vapor diode, also known as a one-way water vapor valve. In other words, the diffusion flow of water vapor in the "open" direction of the water vapor diode is permitted, while the diffusion flow in the "closed" direction of the water vapor diode is suppressed. This function of the multifunctional material system allows for the expulsion of water vapor from the environment inside the enclosure while suppressing the intrusion of water vapor from the environment outside the enclosure.

[0009] When used in building envelopes, the disclosed embodiments of the multifunctional material can reduce installation costs compared to installing a separate membrane layer in the building envelope. Furthermore, in alternative embodiments, the disclosed multifunctional material can omit either the variable permeability layer or the desiccant layer. Such modified multifunctional materials can optimize a subset of performance advantages for different areas of a building, such as bathrooms and kitchens, where humidity control or water vapor transport is the primary concern.

[0010] In one embodiment, a multifunctional material system is provided which may include a variable permeability layer, a desiccant-containing layer, and a vapor-permeable support layer. The variable permeability layer may have vapor permeability that increases with increasing relative humidity. The desiccant-containing layer may be adjacent to the variable permeability layer. The vapor-permeable support layer may be positioned adjacent to at least one of the variable permeability layer and the desiccant-containing layer. When the relative humidity is higher adjacent to the variable permeability layer than adjacent to the desiccant layer, water moves from the variable permeability layer to the desiccant layer in a first direction. When the relative humidity is higher adjacent to the desiccant-containing layer than adjacent to the variable permeability layer, water moves from the desiccant-containing layer to the variable permeability layer in a second direction opposite to it. The velocity of water movement in the first direction is higher than in the second direction when the humidity gradient is reversed.

[0011] In another embodiment, the vapor-permeable layer is interposed between the desiccant-containing layer and the variable-permeability layer. In another embodiment, the permeability of the variable permeability layer increases approximately exponentially with increasing relative humidity.

[0012] In another embodiment, the desiccant-containing layer is substantially homogeneous. In another embodiment, the desiccant-containing layer is a composite material containing desiccant particles embedded in a matrix.

[0013] In another embodiment, the desiccant-containing layer includes a first layer having a matrix formed from a vapor-permeable binder and a second layer having a matrix formed from a variable-permeability binder, wherein the first layer is a variable-permeability layer.

[0014] In another embodiment, at least a portion of the desiccant-containing layer is formed from a desiccant material. The desiccant material may be at least one of silica gel, zeolite, calcium oxide (CaO2), calcium sulfate (CaSO4), lithium chloride (LiCl), clay, or activated carbon.

[0015] In another embodiment, the vapor-permeable layer is formed from polylactic acid (PLA), polytetrafluoroethylene, silicone, natural rubber, synthetic rubber, polystyrene, polymethylpentene (PMP), polycarbonate (PC), polyurethane (PU), or polymethyl methacrylate (PMMA).

[0016] In another embodiment, the variable permeability layer is formed from polyamide or polyvinyl alcohol (PVA). For example, the polyamide may be nylon. In one embodiment, a wall assembly is provided, which may include a wall cavity, an insulating material, and a multifunctional material system. The wall cavity may define a first surface adjacent to the interior of the building and a second surface adjacent to the exterior of the building. The insulating material may be placed within at least a portion of the wall cavity. In one embodiment, the multifunctional material system may include a variable permeability layer, a desiccant-containing layer, and a vapor-permeable support layer. The variable permeability layer may have vapor permeability that increases with increasing relative humidity. The desiccant-containing layer may be adjacent to the variable permeability layer. The vapor-permeable support layer may be placed adjacent to at least one of the variable permeability layer and the desiccant-containing layer. When the relative humidity is higher adjacent to the variable permeability layer than adjacent to the desiccant layer, water moves in a first direction from the variable permeability layer to the desiccant layer. When the relative humidity is higher adjacent to the desiccant-containing layer than adjacent to the variable permeability layer, water moves in a second direction opposite to the desiccant-containing layer. The velocity of water movement in the first direction is higher than in the second direction when the humidity gradient is reversed. The multifunctional material system can be placed on at least one of the first and second surfaces of the wall cavity.

[0017] In one embodiment, a multifunctional material assembly is provided, and the multifunctional material assembly can include a substrate and a multifunctional material system. In one embodiment, the multifunctional material system can include a variable permeability layer, a desiccant-containing layer, and a vapor permeable support layer. The variable permeability layer can have a vapor permeability that increases with an increase in relative humidity. The desiccant-containing layer can be adjacent to the variable permeability layer. A vapor permeable support layer can be disposed adjacent to at least one of the variable permeability layer and the desiccant-containing layer. When the relative humidity is higher adjacent to the variable permeability layer than to the desiccant layer, water moves in a first direction from the variable permeability layer to the desiccant layer. When the relative humidity is higher adjacent to the desiccant-containing layer than to the variable permeability layer, water moves in a second direction opposite thereto from the desiccant-containing layer to the variable permeability layer. The rate of water movement in the first direction is higher than that in the second direction when the humidity gradient is reversed. The multifunctional material system can be disposed on at least one of the first surface and the second surface of the wall cavity. At least one layer of the multifunctional material system can be disposed on the surface of the substrate.

[0018] In another embodiment, the assembly can further include an adhesive layer interposed between the substrate and the layer of the multifunctional material system. In another embodiment, the adhesive layer is the variable permeability layer.

[0019] In another embodiment, the substrate is an oriented strand board (OSB), insulation material, gypsum board, cement board, stucco, drywall, subfloor, roofing material, cladding material, or building film. In another embodiment, the variable permeability layer is disposed on the first surface of the substrate, and the desiccant-containing layer is disposed on the second surface of the substrate facing the first surface of the substrate.

[0020] In another embodiment, the multifunctional material assembly includes a desiccant-containing layer formed from a matrix of the substrate and desiccant particles embedded in the substrate, and the variable permeability layer is deposited on the surface of the desiccant layer.

[0021] In one embodiment, a multifunctional material assembly is provided, which includes a pocketed structure, a plurality of desiccant particles, and a variable permeability layer. The pocketed structure can define one or more pockets having an open side. The plurality of desiccant particles can be disposed within each of the particles of the one or more pockets (e.g., occupying at least a portion of the volume of each pocket). The variable permeability layer can have a vapor permeability that increases with an increase in relative humidity. Also, the variable permeability layer can overlap the open side of each of the one or more pockets.

[0022] The multifunctional material assembly can also include a substrate. The variable permeability layer can be fixed to the substrate.

Brief Description of the Drawings

[0023] [Figure 1] FIG. showing one exemplary embodiment of an operating environment including a multifunctional material structure having a variable permeability layer and a desiccant layer. [Figure 2] FIG. showing a plot of water vapor transmission rate as a function of the humidity of the wall cavity of a selected vapor retarder. [Figure 3] FIG. showing plots of adsorption isotherms for various desiccants including silica gel. [Figure 4a] FIG. showing a plot of the measurement of water flux and pure water transfer in the entire multifunctional material system of FIG. 1. [Figure 4b] FIG. showing a plot of the theoretical simulation of water flux and pure water transfer in the entire multifunctional material system of FIG. 1. [Figure 5a] FIG. showing one exemplary embodiment of a multifunctional material system including a variable permeability layer and a desiccant layer. [Figure 5b] FIG. showing one exemplary embodiment of a multifunctional material system including a desiccant layer in the form of a composite material. [Figure 6] FIG. showing one exemplary embodiment of a multifunctional material system including one or more vapor permeable support layers. [Figure 7a]This figure shows one exemplary embodiment of a multifunctional material system including a desiccant layer having two layers. [Figure 7b] This figure shows one exemplary embodiment of a multifunctional material system in the form of a composite material having a gradient of desiccant concentration over its thickness. [Figure 8] This figure shows one exemplary embodiment of a multifunctional material bonded to a substrate. [Figure 9] This figure shows another exemplary embodiment of a multifunctional material bonded to a substrate. [Figure 10] This figure shows another exemplary embodiment of a multifunctional material bonded to a substrate, where the vapor retarder and desiccant layer are located on opposite sides of the substrate. [Figure 11] This figure shows another exemplary embodiment of a multifunctional material bonded to one surface of a substrate, where the desiccant layer of the multifunctional material system contains desiccant particles embedded in a matrix formed from the substrate material. [Figure 12] This figure shows another exemplary embodiment of a multifunctional material comprising a desiccant layer in the form of a pocketed structure having pockets for containing desiccant particles. [Figure 13] This figure shows the multi-functional material shown in Figure 12 bonded to a substrate. [Figure 14] This figure shows another exemplary embodiment of a smart wall panel, which includes a multifunctional material system having a variable permeability layer wrapped around the edge of the panel, and a vapor-tight seal formed adjacent to and between the smart wall panels. [Modes for carrying out the invention]

[0024] Please note that the drawings are not necessarily to scale. These drawings are intended to show only typical embodiments of the subject matter disclosed herein and should not be construed as limiting the scope of this disclosure.

[0025] This specification discusses embodiments of multifunctional material systems, as well as corresponding manufacturing methods and methods of use as building materials. However, embodiments of this disclosure may be applied to other applications without limitation.

[0026] Figure 1 shows one exemplary embodiment 100 of the operating environment of a wall assembly 102. The wall assembly 102 includes a wall cavity 104 that defines a first surface or inner surface 104a adjacent to an internal environment 106 and a second surface or outer surface 104b adjacent to an external environment 110. Generally, the internal environment 106 can be a space enclosed by the air-conditioned wall assembly 102, while the external environment 110 is an unair-conditioned space. Therefore, when the multifunctional material system 114 is installed on the inner surface 104a of the wall assembly 102, the internal environment 106 can be the interior of a room in a building, and the external environment can be the exterior of a building. However, it can be seen that embodiments of the multifunctional material system can also be used in wall assemblies separating two rooms inside, one of which is air-conditioned and the other unair-conditioned (e.g., an open space or other unair-conditioned space). In either case, the desiccant layer can be placed closest to the unair-conditioned space / environment.

[0027] The wall assembly 102 may further include an insulating material 112 disposed in at least a portion of the wall cavity 104 (for example, between the first surface 104a and the second surface 104b). The wall assembly 102 may further include a multifunctional material system 114. As shown in the figure, the multifunctional material is disposed on the inner surface 104a. However, in alternative embodiments, the multifunctional material system may be disposed on or adjacent to opposing surfaces of the wall cavity (for example, adjacent to the outer surface), or on or adjacent to both the inner and outer surfaces.

[0028] The multifunctional material system 114 may include a variable permeability layer 114a of thickness T and a desiccant-containing layer 114b of thickness L. The variable permeability layer 114a is also referred to herein as a vapor retarder or vapor barrier. As will be discussed in detail below, the desiccant-containing layer 114b may consist substantially entirely of a desiccant material or of a composite material containing a desiccant material embedded in a matrix. However, for simplicity, the desiccant-containing layer 114b is referred to herein as the desiccant layer. The desiccant layer 114b is positioned adjacent to the variable permeability layer 114a. Similarly, as will be discussed in detail below, the desiccant layer may be in contact with the side of the variable permeability layer or separated from the side of the variable permeability layer by one or more layers interposed between them.

[0029] Examples of materials on which the variable permeability layer 114a is formed include polyamide (e.g., nylon), polyvinyl alcohol (PVA), and various polyions. Examples of desiccant materials on which the desiccant layer 114b is formed include one or more of silica gel, zeolite, calcium oxide (CaO2), calcium sulfate (CASO4), lithium chloride (LiCl), clay, or activated carbon. The thickness L of the desiccant layer 114b can be selected from a range of about 0.05 mm to about 20 mm. The thickness T of the variable permeability layer 114a can be selected from a range of about 0.001 mm to about 0.01 mm.

[0030] In embodiments where the desiccant material has a porous structure, the pore size may be in the range of about 0.4 nm to about 100 μm. In other embodiments, the pore size may be about 0.04 nm. In further embodiments, the pore size may be about 100 μm.

[0031] Furthermore, the pore size of the porous desiccant material may vary with its position within the desiccant layer 114b. For example, the pore size may decrease as one approaches a selected side of the desiccant layer 114b (e.g., the side of the desiccant layer 114b closest to the external environment 110).

[0032] The multifunctional material system 114 can be configured to perform various functions, either individually or in any combination. In one embodiment, the multifunctional material system 114 functions as a vapor diode by allowing water to move in a first direction from the variable permeability layer 114a to the desiccant layer 114b at a significantly higher rate than when the humidity gradient is reversed and water vapor is chased in the opposite direction. In another embodiment, the multifunctional material system 114 regulates temperature similar to a phase-change material, except in this context that it is a phase change between adsorbed water and water vapor in the desiccant layer 114b. In a further embodiment, the multifunctional material system 114 regulates relative humidity by adsorbing more water vapor when humidity is rising and releasing water vapor when humidity is falling. These functions improve the energy efficiency, durability, and comfort of a building. The physical principles of these functions and the estimation of the magnitude of their effects will be discussed in detail below.

[0033] [Vapor diode function] An embodiment of the vapor diode function operates as follows: When humidity is high on the side of the variable permeability layer 114a, the permeability to water vapor, also called the permeability coefficient, increases. The desiccant layer 114b has relatively high permeability and adsorbs the water received from the variable permeability layer 114a relatively easily. The water received by the side of the desiccant layer 114b then evaporates into the air adjacent to the desiccant layer 114b. Conversely, when humidity is high on the side of the desiccant layer 114b, the desiccant layer 114b absorbs and separates the water before it reaches the variable permeability layer 114a. In this way, the relative humidity of the variable permeability layer 114a, and therefore the permeability of the variable permeability layer 114a, remains low. Over the humidity fluctuation cycle, net water transfer (e.g., pumping) occurs throughout the multifunctional material system 114. Using this modification function, which is not currently present in building materials, water can be pumped out of the wall cavity 104, thereby improving durability.

[0034] The function of the vapor diode relies on both the nonlinear and asymmetric properties of vapor transport in the multifunctional material system 114. The nonlinearity is provided by a variable permeability layer 114a, whose permeability increases exponentially with relative humidity RH. Figure 2 shows the RH-dependent permeability coefficient of a smart vapor retarder formed from polyamide material (MemBrain, Certaindeed). A two-order-of-magnitude variation in the permeability coefficient can be observed.

[0035] The asymmetry is provided by the desiccant layer 114b, which separates water from only one side of the variable permeability layer 114a (e.g., the side of the variable permeability layer 114a closest to the desiccant layer 114b). Figure 3 shows plots of adsorption isotherms (adsorption as a function of relative humidity at a constant temperature) for silica gel, non-toxic nanoporous minerals, and CaO, clay, molecular sieves, and CASO4. Silica gel adsorbs water in roughly proportion to the relative humidity RH of the ambient air and has the ability to hold up to approximately 37% of its dry weight in water. Water diffuses relatively slowly into the silica gel, which creates a delay between the humidity change on one side of the silica gel layer and the point at which the water content begins to equilibrium on the opposite side. Diffusion constant D SG = 2 x 10 -11 m 2 s -1 and the thickness L of the desiccant layer is L 2 / 2D SG The delay time, scaled as such, characterizes the time it takes for silica gel to separate water from the vapor barrier, allowing the structure to modify vapor transport. For example, with 1 mm of silica gel, the delay time is approximately 7 hours, which is long enough to modify daytime (per day) humidity fluctuations. With 2 mm of silica gel, the delay time is over 115 days, suggesting that a yearly humidity cycle can be modified as well.

[0036] Fluctuations in relative humidity occur most prominently as a result of temperature changes. Since the ability of air to hold water vapor increases with temperature, RH and temperature are inversely correlated. As an example, assume air with a fixed water content starting at 23 °C and 40% relative humidity. As the air warms to 28 °C, the relative humidity drops to 29.7%. As the air cools to 18 °C, the relative humidity rises to 54.5%. These changes can be evaluated using a psychrometric chart or the Magnus formula. Over the same 10 °C temperature range, according to Fig. 2, the transmission coefficient of the smart vapor barrier changes by approximately a factor of 7, and according to Fig. 3, silica gel is expected to exchange approximately 13% of its mass in water when dried in water. Both have a significant effect.

[0037] Measurements of water transport were made across an entire desiccant layer formed from silica gel particles and a prototype multifunctional material system formed with a variable permeability layer of MemBrain (Certainteed). A porous, highly permeable plastic film (on the order of millimeters, e.g., approximately 1 - 10 mm for MemBrain) was used to hold the silica gel particles. This multifunctional material system was subjected to a humidity gradient by using it to cover the water in a wide - mouthed cup, exposing one side to approximately 100% RH and the other side to a laboratory environment of approximately 50% RH. The RH gradient was varied periodically by reversing the structure every day and exposing the opposite side to water vapor. To determine the transfer of water to the silica gel across the entire vapor barrier, the mass of the cup and the multifunctional material system were measured at regular intervals. Fig. 4(a) shows a plot of the measured water flux and the transfer of pure water to the desiccant side as a function of time. The flux of water from the MemBrain side to the silica gel side was more than twice the magnitude of the flux in the reverse direction over the entire cycle. Water moved to the silica gel side at an average rate of about 0.5 g -2 per day. In the context of a medium - sized house with an enclosure area of 200 m -1 ², this pumping rate removes approximately 0.1 L per day from the walls. 2

[0038] The water transport was theoretically modeled using the finite difference method. Specifically, MATLAB® was used to model the diffusion of water throughout the entire prototype multi-functional material system. The simulation was performed assuming a 75 μm thick polyamide layer as a variable permeability layer and a 200 μm thick silica gel layer as a desiccant layer. With an amplitude of 20% and a 48-hour period, and an average RH of 50%, the relative humidity fluctuated sinusoidally on both sides of the simulated multi-functional material system. Both sides were out of phase.

[0039] Figure 4(b) shows a plot of the simulated water flux across the entire multi-functional material system of the prototype, as well as the integrated mass of water accumulated on the desiccant layer side. The water flux from the variable permeability layer side (polyamide side) to the desiccant layer side was twice as large as the peak flux in the reverse direction throughout the entire cycle. The amount of water was approximately 0.1 gm³. -2 day -1 It accumulated on the desiccant layer side at an average rate.

[0040] It can be understood that the pumping effect provided by the function of the vapor diode works even when the humidity fluctuations on both sides are in phase, that is, even when there is no change in humidity. The only requirement for pumping is that the humidity fluctuates periodically. As an example, when the humidity is high on both sides of the multifunctional material system 114, water vapor diffuses from both sides to the desiccant layer 114b (e.g., via adjacent air and the variable permeability layer 114a) at a high transport rate through the variable permeability layer 114a. The distribution of water in the desiccant layer 114b can slowly equilibrate (for example, if the desiccant layer 114b is about 1 mm thick, the time required for complete equilibration may be several hours). Subsequently, when the humidity is low on both sides of the multifunctional material system 114, water vapor diffuses out of the multifunctional material system 114 from both sides of the variable permeability layer 114a and the side of the desiccant layer 114b. However, the diffusion rate on the side of the variable permeability layer 114a is significantly slower than when water vapor enters. Thus, when the velocities of water entering and leaving through the variable permeability layer 114a are unbalanced, a net transfer of water (pumping) occurs in the direction of the desiccant layer 114b.

[0041] [Phase change function] As the temperature rises, the RH decreases, and water evaporates from the desiccant layer 114b. Conversely, as the temperature decreases, the RH increases, and the desiccant layer 114b absorbs water. In these two processes, the absorbed latent heat regulates the temperature, and the released latent heat reduces the demands of the HVAC system. This principle is the same as that of phase-change materials, except that the surrounding water is the phase that changes the substance.

[0042] For every gram of water that evaporates, approximately 2500 J is absorbed from the environment. This represents the sum of the latent heat of boiling and the small surface bonding energy. As an example, the latent heat density of silica gel can be approximately 925 kJ / kg. However, in reality, only a portion of this latent heat is usable. Generally, the desiccant layer 114b is neither completely dry nor completely filled with water under normal operating conditions.

[0043] A more realistic estimation of the latent heat density can be based on the same 10°C temperature change already considered and the fact that the adsorption isotherm in Figure 3 does not change significantly with temperature. Over this temperature increase, the total amount of water adsorbed or released by the silica gel desiccant is expected to be about 13% of the dry mass. This corresponds to a latent heat density of about 325 kJ / kg. In contrast, the latent heat densities of commercially available phase change materials range from 120 kJ / kg to 220 kJ / kg. It can be seen that desiccant materials can be fabricated to release the same latent heat over a narrower temperature range. In other words, the adsorption isotherm needs to be steeper in the relevant RH range.

[0044] At a cost of approximately $1 / kg, silica gel is a relatively inexpensive desiccant material. It can supply latent heat at approximately 320 kJ / $. Commercial PCM costs much more, with cheaper options selling for around 36 kJ / $ (based on 120 kJ / kg and $1.50 / lb ($3.30 / kg)). Furthermore, its density is ρ SG = 1280 kgm -3 In that case, a 1mm silica gel layer is 1.28kgm -2 It has a surface mass of m and is approximately 416 kJm -2 It provides latent heat. In contrast, commercially available gypsum board using PCM (e.g., National Gypsum ThermalCORE) provides 250 kJm -2 That is the case.

[0045] [Humidity buffer function] A 1mm thick silica gel desiccant can hold up to approximately 450g of water per square meter of wall. However, more realistically, this value is approximately 150gm -2 This is closer to the amount of water exchanged between the wall and the internal environment under normal conditions. In a medium-sized house, the multi-functional material system 114 can adsorb or release approximately 30 liters of water. This significantly improves comfort, reduces the energy demand of the HVAC system, and eliminates the need for electric humidifiers or dehumidifiers.

[0046] Finally, it's important to note that silica gel is commonly misunderstood as a hazardous material. This stems from the "Do not eat" warning printed on the familiar white silica gel packets found in packaging (such as shoe boxes). However, silica gel itself is not toxic. Instead, the warning is present because silica gel beads often contain cobalt(II) chloride, which is carcinogenic. Cobalt(II) chloride acts as a moisture indicator, changing color from blue to pink as the moisture content increases. Since there is no need to include cobalt(II) chloride in construction materials, using silica gel desiccant does not pose any obvious safety concerns.

[0047] [Function control] The requirements and relative importance of the three functions of the multifunctional material system 114 may depend on the location of the building envelope in which the multifunctional material system 114 is used and the climate in which the building is located. In one embodiment, the ability of the multifunctional material system 114 to regulate humidity may be more desirable inside the building than outside. In another embodiment, the vapor diode function may be more desirable in humid climates than in dry climates. Methods for adjusting manufacturing parameters or material parameters are available to control the performance characteristics of the multifunctional material system 114. This makes it possible to optimize the performance of different building materials incorporating the multifunctional material system 114 for specific applications.

[0048] The timescale for which the multifunctional material system 114 corrects humidity fluctuations is determined by the timescale required for water to diffuse through the desiccant layer 114b and reach a steady concentration. For a continuous desiccant layer 114b of thickness L, the timescale t is determined by the following equation.

[0049]

number

[0050] Furthermore, the desiccant layer 114b can also be in the form of a composite material containing multiple desiccant particles held in close proximity to each other within the matrix. In this configuration, if the diffusivity of water in the matrix is ​​significantly higher than the diffusivity of water in the desiccant particles, the longest time scale over which the modification can be observed is scaled as follows:

[0051]

number

[0052] In the equation, r is the radius of the desiccant particle. If the desiccant layer 114b is composed of desiccant particles with a size distribution, the relaxation time distribution is revealed by the time response of the desiccant layer 114b. If the diffusivity of water in the matrix is ​​significantly lower than the diffusivity of water in the desiccant particles, the time scale becomes much longer and can be described by a percolation model.

[0053] The latent heat capacity of the temperature-regulating multifunctional material system 114 is proportional to the amount of water exchanged between the condensed phase and the vapor phase. Assuming sufficient time for equilibrium, the latent heat that can be stored or released from a continuous desiccant layer 114b is proportional to its thickness. However, assuming only a finite amount of time t, the portion of the desiccant layer 114b where the water concentration changes significantly has the following finite thickness.

[0054]

number

[0055] The circadian cycle sets the relevant time scale for energy efficiency applications and consequently determines the maximum effective thickness of the continuous desiccant layer 114b. As described above, by providing the desiccant layer 114b in the form of a composite material, the effective amount of latent heat available in the multifunctional material system 114 can be increased, and the matrix has a high water vapor diffusivity. The desiccant particles must be small enough so that the water content can be equilibrated within about 12 hours. Since water vapor can diffuse more rapidly through the matrix, the latent heat content obtained from such a desiccant layer 114b increases with thickness and exceeds the following values.

[0056]

number

[0057] The maximum effective thickness is scaled as follows:

[0058]

number

[0059] In the formula, D M This is the effective diffusion rate of water vapor in the matrix. Phase change materials are effective in reducing the heating and cooling demands of a building's HVAC system when they are incorporated outwards from the building envelope in a location where the temperature swings around an internal setpoint.

[0060] Furthermore, the ability of the multi-functional material system 114 to regulate humidity is proportional to the amount of water that can be exchanged between the condensed phase and the vapor phase. The same measures as described above may be used to adjust this ability.

[0061] The permeability coefficient of the variable permeability layer 114a is inversely proportional to its thickness. Therefore, by manufacturing a variable permeability layer 114a of appropriate thickness, the RH-dependent permeability coefficient curve can be scaled to the desired coefficient. Controlling the overall permeability coefficient is important because it affects how effectively the multifunctional material system 114 can utilize humidity fluctuations to pump water vapor. This is also important because it must be possible to increase the potential drying capacity of the wall assembly and therefore increase permeability in at least one direction. For example, in cold climates, wall assemblies are often designed to dry on the outside, and the exterior of a building used as an air and weather barrier outside the substrate has high permeability to water vapor. By replacing the exterior of a building with the multifunctional material system 114, the performance of the envelope can be improved without sacrificing potential drying capacity, provided that the variable permeability layer 114a is manufactured to have a sufficiently high permeability coefficient under humid conditions. In other words, a relatively low permeability coefficient is not a problem when the wall cavity 104 is dry.

[0062] To control the performance of the multifunctional material system 114, the microstructure and properties of the desiccant material can be engineered. For example, the pore size distribution and the hydrophilicity of the desiccant material surface affect the shape of the adsorption isotherm. Nanoporous materials with relatively hydrophobic surfaces adsorb little to no water until the critical humidity value of the air is exceeded. In this respect, liquid water is energetically more likely to condense inside the narrowest constrictions of the pores. This effect is controlled by capillary action and therefore manifests at higher humidity values ​​in larger pores. As another example, different desiccant materials preferentially adsorb water vapor in the RH range indicated by the steepness of the slope of the adsorption isotherm (Figure 3). Since they effectively buffer RH in a specific range of interest, specific materials can be selected, or multiple desiccant materials can be combined to adjust the range in which the mixture can efficiently buffer RH. Therefore, the material or microstructure (e.g., pore size) can be selected to most effectively buffer relative humidity within the selected RH range (e.g., the slope of the adsorption isotherm is maximized within the selected RH range).

[0063] [Example of a multifunctional material architecture] The architectural embodiment of the multifunctional material system 114 described above can be realized as a self-supporting film. Figure 5A shows a multifunctional material system 500 including a variable permeability layer 114a bonded to a desiccant layer. As shown, the desiccant layer 114b may be substantially homogeneous.

[0064] Figure 5B shows another embodiment of the multifunctional material system 500 in the form of a multifunctional material system 550. As shown, the multifunctional material system 550 includes a variable permeability layer 114a and a desiccant layer 114b in the form of a composite desiccant layer 554 containing a first component and a second component. For example, the first component may be a matrix 556, and the second component may be a desiccant material 560 embedded within the matrix 556. The geometry of the desiccant material 560 may vary. In one embodiment, the desiccant material 560 may take the form of a plurality of desiccant particles embedded within the matrix 556. In a particular embodiment, the desiccant particles may be substantially uniform in size (e.g., diameter) and shape. In other embodiments, the desiccant particles may have a size distribution (e.g., a nearly normal distribution, a binary distribution, etc.). For example, the size of the desiccant particles may range from about 0.05 mm to about 5 mm.

[0065] The matrix 556 of the composite desiccant layer 552 may be formed from a material with high water vapor permeability. In one embodiment, a material with permeability exceeding 5 US perms (e.g., exceeding 10 perms) can be considered a vapor-permeable material. Examples of the matrix 556 include binders, foams (e.g., thermal insulation materials), meshes, fiber mats, filaments, textiles, fabrics, drywalls, substrates, coverings, and structural insulation panels (SIPs). Examples of binder materials include polylactic acid (PLA), polytetrafluoroethylene (e.g., colloidal polytetrafluoroethylene), polyurethane (thermoplastic or foamed), silicone, natural rubber, synthetic rubber, polymethylpentene (PMP), polystyrene (PS), polycarbonate (PC), polyvinyl alcohol (PVA), or polymethyl methacrylate (PMMA). Other polymers and resins are also intended.

[0066] The desiccant material 560 within the matrix 556 may be formed from any of the desiccant materials described above in the context of the desiccant layer 114b. Examples of desiccant materials include one or more of silica gel, zeolite, calcium oxide (CaO2), calcium sulfate (CASO4), lithium chloride (LiCl), clay, or activated carbon. Combinations of two or more different desiccant materials are also conceivable.

[0067] In further embodiments, the multifunctional material system 114 can be modified to include one or more vapor-permeable layers (e.g., layers with very high permeability to water vapor). In certain embodiments, these vapor-permeable layers can provide mechanical support to the multifunctional material system 114 without fundamentally altering its function. In other embodiments, the vapor-permeable material forming the vapor-permeable layer may be a material with permeability greater than 10 US perms, and the vapor-impermeable material may be a material with permeability less than 0.1 US perms. Examples of materials forming the vapor-permeable layer include fabrics, meshes, fiber mats, porous materials, silicone, natural rubber, synthetic rubber, polystyrene (e.g., high-impact polystyrene (HIPS)), polymethylpentene (PMP), polycarbonate (PC), polyurethane (PU), and polymethyl methacrylate (PMMA).

[0068] Figure 6 shows another embodiment of the multifunctional material system 114 in the form of a multifunctional material system 600. The multifunctional material system 600 is similar to the multifunctional material system 500, with the addition of a vapor permeable layer 602 for support. As shown in Figure 6, the vapor permeable layer 602 is located on both sides of the desiccant layer 114b, and the variable permeability layer 114a is located on one side of the vapor permeable layer 602 closest to the internal environment 106. However, in alternative embodiments, one or more vapor permeable layers may be employed on both sides of the desiccant layer. In further embodiments, the positions of the vapor permeable layers and the variable permeability layers may be swapped. That is, one or more vapor permeable layers may be positioned in contact with the variable permeability layer, the desiccant layer, or both. In other embodiments, the vapor permeable layers may be configured to provide functions such as water repellency. Furthermore, it can be understood that any embodiment of the multifunctional material systems disclosed herein may include one or more vapor permeable layers as needed, although these are not illustrated.

[0069] Embodiments of the vapor permeable layer 602 can employ various configurations. In one embodiment, the mechanical properties of the vapor permeable layer 602 can be adjusted within a specific range. Examples of mechanical properties include stiffness (e.g., having an elastic modulus greater than a predetermined value), flexibility (e.g., having an elastic modulus lower than a predetermined value or a yield stress smaller than a predetermined value), impact resistance (e.g., having a hardness greater than a predetermined value), sound absorption (e.g., sound attenuation greater than a predetermined value), tear resistance (e.g., having fracture toughness greater than a predetermined value), strength (e.g., having a tensile strength greater than a predetermined value), or peel resistance (e.g., having a peel strength greater than a predetermined value).

[0070] In further embodiments, the desiccant layer 114b may include two or more layers. Figure 7a shows another embodiment of the multifunctional material system 114 in the form of the multifunctional material system 700. As shown, the desiccant layer 114b includes a first desiccant layer 702 and a second desiccant layer 704. The first desiccant layer 702 and the second desiccant layer 704 may be composites comprising a matrix and a desiccant material (e.g., desiccant material 560) embedded therein, as described above. In certain embodiments, the matrix may function as a binder for holding the embedded desiccant material. As an example, the first desiccant layer 702 may include a matrix formed from the same material as described above with respect to the variable permeability layer 114a. The second desiccant layer may include a matrix formed from the same material as described above with respect to the vapor permeability layer 602. Therefore, the matrix of the first desiccant layer 702 can perform the function of the variable permeability layer 114a as described above.

[0071] In an alternative embodiment, a single layer of the multifunctional material system 114 can provide the functions of both the desiccant layer 114b and the variable permeability layer 114a. Figure 7b shows the multifunctional material system 114 in the form of a multifunctional material system 750, which includes a composite desiccant layer 752 comprising a matrix formed from the materials described above with respect to the variable permeability layer 114a, and a desiccant material 560 embedded therein. The concentration (e.g., volume fraction) of the desiccant material 560 can vary throughout the thickness. For example, the concentration of the desiccant material 560 in the first portion 754 of the multifunctional material system 750 may be relatively low, and the concentration of the desiccant material 506 in the second portion 756 of the multifunctional material system 750 may be relatively low. In a particular embodiment, the concentration of the desiccant material 560 in the high-concentration portion 756 may be about three times the concentration of the desiccant material 560 in the low-concentration portion 754. With this configuration, the low-concentration portion 754 of the multifunctional material system 750 can effectively function as a variable permeability layer 114a, and the high-concentration portion 756 of the multifunctional material system 750 can effectively function as a desiccant layer 114b. The thickness of the low-concentration portion 754 can be in the range of approximately 0.001 mm to approximately 0.1 mm, and the thickness of the high-concentration portion 756 can be in the range of approximately 0.05 mm to approximately 20 mm. As further shown in Figure 7, the multifunctional material system may optionally include a vapor-permeable layer 602 bonded to one or both sides of the composite desiccant layer 752.

[0072] In certain embodiments, the multifunctional material system 114 can be incorporated into a building in the form of a separate membrane, such as a vapor barrier or building exterior. In other embodiments, it may be desirable to add multifunctionality to the building envelope without increasing the complexity of the building envelope. Therefore, the multifunctional material system can also be integrated with one or more elements of the building envelope, such as cladding, underlayment, roofing, insulation, or interior panels.

[0073] As an example, a multifunctional material system 114 can be used to form a functional building material. As shown in Figure 8, the multifunctional material assembly 800 is formed by fixing any embodiment of the multifunctional material system 114 discussed herein to a base material 802.

[0074] In certain embodiments, the multifunctional material system 114 can be fixed to the substrate 802 by a vapor-permeable adhesive 804. The permeability of the vapor-permeable adhesive 804 can be selected from a range of 5 to 100 perms. Examples of vapor-permeable adhesives include polyvinyl alcohol and rubber grease. Examples of substrates that are vapor-permeable include oriented strand board (OSB), thermal insulation (e.g., rigid foam insulation), gypsum board, cement board, decorative plaster, drywall, underlayment, roofing material, covering material, or building film, or other building material. With this configuration, all three functions of the multifunctional material system 114 can operate if the substrate 802 and adhesive 804 are permeable to water vapor.

[0075] In configurations where at least one of the substrates or adhesives is relatively impermeable to water vapor and functions as a vapor barrier (e.g., with permeability of less than 0.01 perms), the multifunctional material system may cease to function as a vapor diode. However, temperature and humidity control functions may be retained.

[0076] In alternative embodiments, adhesives can be omitted, and other mechanisms can be employed to secure the substrate to the multifunctional material system. In one embodiment, nails, screws, or other fastening mechanisms may be employed. In another embodiment, a boundary may exist between the substrate and the multifunctional material system (e.g., a variable permeability layer). Within the boundary, the variable permeability layer may expand within the substrate and be mechanically locked therein, the substrate may expand within the variable permeability layer and be mechanically locked therein, or a combination of these may occur.

[0077] In further alternative embodiments, the functions of the adhesive 804 and the variable permeability layer 114a can be combined into a single layer. Figure 9 shows an embodiment of the multifunctional material assembly 800 in the form of a multifunctional material assembly 900 including a substrate 802, a desiccant layer 114b, and a variable permeability adhesive layer 902. The variable permeability adhesive layer 902 is interposed between the substrate 802 and the desiccant layer 114b and is configured to attach the desiccant layer 114b to the substrate 802. The variable permeability adhesive is further configured to provide the function of the variable permeability layer as described above. Examples of variable permeability adhesives include polyvinyl alcohol (PVA) and rubber cement. By combining multiple functions (adhesion and variable permeability) into the variable permeability adhesive layer 902, the number of layers required to achieve all three functions of the multifunctional material system 114 in the multifunctional material assembly 900 can be reduced. This simplification can reduce the manufacturing cost of the multifunctional material assembly 900.

[0078] In a further embodiment of the multifunctional material assembly 800, the variable permeability layer 114a and the desiccant layer 114b may be separated from each other by one or more intervening layers. Figure 10 shows another embodiment of the multifunctional material assembly 800 in the form of a multifunctional material assembly 1000. As shown, the substrate 802 is interposed between the variable permeability layer 114a and the desiccant layer 114b. Thus, the variable permeability layer 114a and the desiccant layer 114b are located on opposing sides of the substrate 802. With this configuration, the functionality of the multifunctional material system 114 can be maintained as long as the substrate 802 is permeable to water vapor. Optionally, one or more vapor permeable layers 602 may be interposed between the variable permeability layer 114a and the desiccant layer 114b.

[0079] Figure 11 shows the multifunctional material assembly 800 in the form of a multifunctional material assembly 1100 including a composite desiccant layer 1102 in which a desiccant material 560 is embedded in a matrix formed from the material of the base material 802. A variable permeability layer 114a is further attached to one side of the composite desiccant layer 1120. As previously mentioned, the base material can be formed from materials including oriented strand board (OSB), thermal insulation (e.g., rigid foam insulation), gypsum board, cement board, plaster, drywall, underlayment, roofing material, covering material, or building film. By combining the functions of the desiccant material 560 with the additional functions of the base material 802, the number of layers required to achieve all three functions of the multifunctional material system 114 and the functions of the base material 802 can be reduced. This simplification can reduce the manufacturing cost of the multifunctional material assembly 1100.

[0080] Embodiments of the multifunctional material system 114 may employ further architectures. Figure 12 shows another embodiment of the multifunctional material system 114 in the form of a pocketed multifunctional material system 1200. The pocketed multifunctional material system 1200 includes a pocketed frame 1202 defining one or more pockets 1204. A desiccant material 560 (e.g., desiccant particles) may occupy at least a portion of the volume of the pockets 1204. As shown in Figure 12, the pocketed frame 1202 defines one or more pockets 1204, each having an opening 1206 at one end. A variable permeability layer 114a may be positioned to extend across the entire opening(s) 1206 of the pocket(s) 1204.

[0081] In a particular embodiment, the pocket 1204 contains only the desiccant material 560; that is, there is no binder or adhesive. Therefore, the walls of the pocket 1204 (e.g., the pocketed frame 1202 and the variable permeability layer 114a) simply serve to hold the desiccant material 560 within the pocket 1204.

[0082] The pocketed frame 1202 may be formed from a material that is permeable to water vapor. For example, the pocketed frame 1202 may be formed from the same materials as described above for the vapor-permeable layer 602 (e.g., one or more of polylactic acid (PLA), natural rubber, synthetic rubber, polymethylpentene (PMP), polystyrene (PS), polycarbonate (PC), polydimethylsiloxane (PDM), or wood). In alternative embodiments, the permeability of the pocketed structure may be achieved by forming the pocketed structure using a material containing multiple pores. For example, the pocketed structure may be formed from a mesh in which the openings are smaller than the diameter of the desiccant particles. Further examples of materials that can form a pocketed structure include one or more of fabrics, fiber mats, open-cell foams, or perforated plastics.

[0083] Figure 13 shows the multifunctional material system 1200 of Figure 12 fixed to a substrate 802 to form a multifunctional material assembly 1300. As shown, a variable permeability adhesive layer 902 is interposed between the substrate 802 and the pocketed frame 1202. However, in alternative embodiments, other fastening mechanisms may be employed. Optionally, one or more vapor-permeable layers (e.g., facing the substrate) can be provided to support the pocketed structure.

[0084] A building typically includes a building envelope that separates air-conditioned spaces from unair-conditioned spaces. The building envelope can provide resistance to the conduction of air, water, heat, light, and / or noise. It is sometimes desirable for the building envelope to be nearly continuous in order to provide the desired conduction resistance; that is, gaps within the building envelope have little effect on the desired conduction resistance.

[0085] As described above, embodiments of the multifunctional material assembly 800 discussed herein can be used as building envelopes. When the base material 802 is a relatively flexible material, the multifunctional material assembly 800 can be wrapped around the building frame. When such flexible multifunctional assemblies are wrapped in a substantially overlapping manner, gaps can be avoided.

[0086] Under conditions where the base material 802 is a relatively rigid material, embodiments of the multifunctional material assembly 800 can be formed as panels. The panels can be fixed to the building frame to provide a building envelope. However, it can be understood that gaps or seams may exist between adjacent panels of the multifunctional material assembly 800. If left unaddressed, these gaps may allow water vapor to bypass the multifunctional material system 114.

[0087] To address potential issues with gaps between panels of a multifunctional material assembly 800, it can be employed as a building envelope. Figure 14 shows a portion of a building envelope 1400 containing multiple multifunctional material assemblies 800 in the form of a multifunctional material panel 1402. As shown, the multifunctional material panel 1402 includes a core 1404 and a variable permeability layer 114a extending around three sides of the core 1404 and along a portion of the fourth side to form a lip 1406. The side of the core 1404 not completely covered by the variable permeability layer 114a may face an air-conditioned environment (e.g., an external environment 110), while the opposite side of the core 1404 covered by the variable permeability layer 114a may face an air-conditioned environment (e.g., an internal environment 106). The core 1404 may include a substrate 802 and a desiccant layer 114b. In one embodiment, the substrate 802 and the desiccant layer 114b may be separate layers. In another embodiment, the core may be in the form of a composite desiccant layer 1102 in which the desiccant material 560 is embedded in the matrix of the substrate 802.

[0088] By applying a sealing material, a substantially vapor-tight seal 1410 can be formed along the gap 1412 between adjacent multifunctional material panels 1402. The sealing material can be any material that substantially inhibits the conduction of water vapor.

[0089] In the case of a functional material panel 1402 cut to size, a new lip can be provided along the cut edge along with the variable permeability layer 114a. Furthermore, a damaged multifunctional material panel 1402 can be joined to other parts of the multifunctional material panel 1402 after sealing its edges and the edges of the gap 1412.

[0090] The sealing material can employ a variety of configurations. In one embodiment, the sealing material may be an adhesive vapor barrier tape that is substantially impermeable to water vapor. A lip is present to ensure that the adhesive vapor barrier tape seals the variable permeability layer 114a. Instead of, or in addition to, the adhesive vapor barrier tape, a vapor-impermeable liquid sealant can be used to form the seal 1410. In such embodiments, the lip can be omitted.

[0091] A method for manufacturing a multifunctional material assembly for use as a building material is further provided. A base material 802 is provided in a single operation. As described above, embodiments of the base material include vapor-permeable, oriented strand board (OSB), thermal insulation (e.g., rigid foam insulation), gypsum board, cement board, decorative plaster, drywall, substrate, roofing material, covering material, or building film, or other building material.

[0092] A multifunctional material assembly can be formed by depositing layers of a multifunctional material system onto a substrate (e.g., by diffusion or spray coating) or by incorporating them into the substrate. In embodiments where the multifunctional material system includes multiple layers, the layers can be deposited sequentially. In certain embodiments, the multifunctional material assembly can be prepared remotely and fixed to a building frame. In other embodiments, the substrate can be mounted to a building frame, and then the multifunctional material system can be deposited sequentially onto the substrate.

[0093] Embodiments of vapor-permeable layers and variable-permeability layers can be deposited from an aqueous solution. Once the aqueous solution with the deposited layers dries, it can adhere to a substrate (e.g., a substrate, the other of the variable-permeability layer or vapor-permeable layer, a desiccant layer, etc.), providing a substantially continuous film of the vapor-permeable layer or the variable-permeability layer.

[0094] The desiccant layer can be constructed in various ways. In one embodiment, the desiccant layer can be deposited from a slurry containing a binder and desiccant particles. The desiccant particles may be one or more of silica gel, zeolite, calcium oxide (CaO2), calcium sulfate (CASO4), lithium chloride (LiCl), clay, or activated carbon. Examples of binders include polylactic acid (PLA), polytetrafluoroethylene (e.g., colloidal polytetrafluoroethylene), polyurethane (thermoplastic or foamed), silicone, natural rubber, synthetic rubber, polymethylpentene (PMP), polystyrene, polycarbonate (PC), polyvinyl alcohol (PVA), or polymethyl methacrylate (PMMA). Other polymers and resins are also intended.

[0095] In embodiments of a composite desiccant layer where the matrix is ​​a foam (e.g., polyurethane foam), the foam may be formed from the reaction of two or more components that release gas. The foam matrix may be heated and dried, or it may self-heat from the reaction of two or more components. Once the deposited composite desiccant layer is dry, it can adhere to a substrate, providing a substantially continuous film of the composite desiccant layer.

[0096] Alternative embodiments of the composite desiccant layer can be extruded continuously. In one embodiment, the desiccant layer can be extruded from a mixture of a thermoplastic polymer and desiccant particles. The desiccant particles may be one or more of silica gel, zeolite, calcium oxide (CaO2), calcium sulfate (CASO4), lithium chloride (LiCl), clay, or activated carbon. Examples of thermoplastic resins include natural rubber, synthetic rubber, polylactic acid (PLA), polystyrene (e.g., high-impact polystyrene [HIPS]), polymethylpentene (PMP), polycarbonate (PC), polyurethane (PU), polymethyl methacrylate (PMMA), or polyvinyl alcohol (PVA).

[0097] The exemplary technical effects of the methods, systems, and devices described herein include, in non-limiting examples, a reduction in the mean humidity inside the wall cavity due to a water vapor pumping effect, and a resulting reduction in the risk of one or more of mold, decay, mildew, and dust mites. Further exemplary technical effects include stabilization of the relative humidity inside the enclosure and, in connection with this, improved comfort and air quality. Additional exemplary technical effects include stabilization of the internal temperature and, when the multifunctional membrane is located inside the enclosure, a reduction in the energy intensity of heating and cooling. Other technical effects include, when the multifunctional material system is located externally, a further reduction in the energy intensity of heating and cooling so that the external surface can be cooled by evaporation during the day using water collected from the environment at night. Further technical effects include a reduction in the risk of water condensation inside the wall as a result of weakening the humidity swing inside the wall cavity.

[0098] To provide an overall understanding of the structure, function, manufacturing and use principles of the systems, devices, and methods discussed herein, certain exemplary embodiments have been described. One or more of these embodiments are shown in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and shown in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of the invention is defined solely by the claims. Features illustrated and described in relation to one exemplary embodiment can be combined with features of other embodiments. Such modifications and variations are intended to be within the scope of the invention. Furthermore, in this disclosure, components with similar names in embodiments generally have similar features, and therefore, in a particular embodiment, each feature of each component with a similar name is not necessarily fully detailed.

[0099] The approximate language used throughout this specification and the claims of this application may be applied to modify any quantitative expression that may vary within an acceptable range without causing a change in the fundamental function of the relevant expression. Accordingly, values ​​modified by the terms “About,” “approximately,” and “substantially” are not limited to specified precise values. In at least some cases, the approximate language may correspond to the precision of an instrument used to measure a value. Throughout the specification and the claims, scope limitations may be combined and / or modified to include all sub-scopes that are specified and contained therein unless otherwise specified by context or language.

[0100] Those skilled in the art will understand the further features and advantages of the present invention based on the embodiments described above. Therefore, this application is not limited to those illustrated and described, unless additional claims specify otherwise. All publications and references cited herein are expressly incorporated by reference.

Claims

1. A multifunctional material system having a first side and a second side opposite to the first side, A variable permeability layer configured to be applied to the first surface of a substrate, A desiccant layer applied to the surface of the variable permeability layer, which is adjacent to the substrate and faces another surface of the variable permeability layer, Equipped with, In both the first and second sides of the multifunctional material system, when humidity is high, water or water vapor flows into the desiccant layer through the variable permeability layer. In both the first and second sides of the multifunctional material system, when humidity is low, water or water vapor flows out from the desiccant layer through the variable permeability layer. The rate at which water or water vapor flows into the desiccant layer through the variable permeability layer when humidity is high is greater than the rate at which water or water vapor flows out of the desiccant layer through the variable permeability layer when humidity is low. Multifunctional material system.

2. The system according to claim 1, further comprising a vapor permeable layer, wherein the vapor permeable layer is interposed between the desiccant layer and the variable permeability layer.

3. The system according to claim 1, wherein the desiccant layer is substantially homogeneous.

4. The system according to claim 1, wherein the desiccant layer is a composite material containing desiccant particles embedded in the matrix.

5. At least a portion of the desiccant layer is formed from a desiccant material, and the desiccant material is silica gel, zeolite, calcium oxide (CaO2). ２ ), calcium sulfate (CaSO4) ４ The system according to claim 1, wherein the system is at least one of lithium chloride (LiCl), clay, or activated carbon.

6. The system according to claim 1, wherein the variable permeability layer is formed from polyamide or polyvinyl alcohol (PVA).

7. The system according to claim 6, wherein the polyamide is nylon.

8. A multi-functional material assembly, Substrate and A first layer deposited on the substrate, comprising the first layer containing polyamide or polyvinyl alcohol (PVA), A desiccant layer deposited on the first layer, comprising desiccant particles embedded in a matrix, wherein the matrix is ​​a binder material formed from one or more vapor-permeable materials, Equipped with, In both the first and second sides of the multifunctional material assembly, when humidity is high, water or water vapor flows through the first layer into the desiccant layer. In both the first and second sides of the multifunctional material assembly, when humidity is low, water or water vapor flows out from the desiccant layer through the first layer. When humidity is high, the rate of inflow of water or water vapor into the desiccant layer through the first layer is greater than the rate of outflow of water or water vapor from the desiccant layer through the first layer when humidity is low. The first layer and the desiccant layer are separate and independent of each other. Multifunctional material assembly.

9. The assembly according to claim 8, wherein the substrate is one of oriented strand board (OSB), thermal insulation material, gypsum board, cement board, decorative plaster, drywall, underlayment, roofing material, covering material, or building film.

10. The desiccant particles are silica gel, zeolite, calcium oxide (CaO ２ ), calcium sulfate (CaSO4) ４ The assembly according to claim 8, comprising one or more of ), lithium chloride (LiCl), clay, or activated carbon.

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